[Bug tree-optimization/94443] New: [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[Bug tree-optimization/94443] New: [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

            Bug ID: 94443
           Summary: [10 Regression] 510.parest_r and 526.blender_r ICE:
                    verify_ssa failed since
                    r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
                CC: linkw at gcc dot gnu.org
  Target Milestone: ---

These 2 SPEC benchmarks fail with -O3 -march=znver2, I'm reducing that right
now.

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |10.0
     Ever confirmed|0                           |1
           Priority|P3                          |P1
           Assignee|unassigned at gcc dot gnu.org      |marxin at gcc dot gnu.org
           Keywords|                            |needs-reduction
             Status|UNCONFIRMED                 |NEW
             Blocks|                            |26163
   Last reconfirmed|                            |2020-04-01


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26163
[Bug 26163] [meta-bug] missed optimization in SPEC (2k17, 2k and 2k6 and 95)

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
$ cat sparsity_pattern.ii
int a;
unsigned *b;
class A {
  A();
};
A::A() {
  for (unsigned i; i <= a; ++i, ++b)
    ;
}

$ g++ -O3 -march=znver2 sparsity_pattern.ii
sparsity_pattern.ii: In constructor 'A::A()':
sparsity_pattern.ii:6:1: error: missing definition
    6 | A::A() {
      | ^
for SSA_NAME: _59 in statement:
_36 = _59;
during GIMPLE pass: vect
sparsity_pattern.ii:6:1: internal compiler error: verify_ssa failed
0x12bc552 verify_ssa(bool, bool)
        /home/marxin/Programming/gcc/gcc/tree-ssa.c:1208
0xfbcd55 execute_function_todo
        /home/marxin/Programming/gcc/gcc/passes.c:1992
0xfbd9fe execute_todo
        /home/marxin/Programming/gcc/gcc/passes.c:2039
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

--- Comment #2 from Martin Liška <marxin at gcc dot gnu.org> ---
Or a simple C code:

$ cat tc.i
int a;
unsigned *b;

void foo()
{
  for (unsigned i; i <= a; ++i, ++b)
    ;
}

$ gcc -O3 -march=znver2 tc.i
tc.i: In function 'foo':
tc.i:4:6: error: missing definition
    4 | void foo()
      |      ^~~
for SSA_NAME: _59 in statement:
_36 = _59;
during GIMPLE pass: vect
tc.i:4:6: internal compiler error: verify_ssa failed
0x1052d12 verify_ssa(bool, bool)
        /home/marxin/Programming/gcc/gcc/tree-ssa.c:1208
0xd4b065 execute_function_todo
        /home/marxin/Programming/gcc/gcc/passes.c:1992
0xd4bd0e execute_todo
        /home/marxin/Programming/gcc/gcc/passes.c:2039
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

Kewen Lin <linkw at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |linkw at gcc dot gnu.org

--- Comment #3 from Kewen Lin <linkw at gcc dot gnu.org> ---
Thanks for reporting this, confirmed.

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

--- Comment #4 from Kewen Lin <linkw at gcc dot gnu.org> ---
This case has one conversion insn generated after bit_field_ref, the patch
introduces one stupid mistake to use gsi_insert_before instead of
gsi_insert_seq_before, it leads to miss the conversion insn.  The below patch
makes it work. It also polishes copy related code a bit although not really
necessary to make this case pass.

diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index c9b6534..4c2c9f7 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -8050,7 +8050,7 @@ vectorizable_live_operation (stmt_vec_info stmt_info,
   if (stmts)
     {
       gimple_stmt_iterator exit_gsi = gsi_after_labels (exit_bb);
-      gsi_insert_before (&exit_gsi, stmts, GSI_CONTINUE_LINKING);
+      gsi_insert_seq_before (&exit_gsi, stmts, GSI_SAME_STMT);

       /* Remove existing phi from lhs and create one copy from new_tree.  */
       tree lhs_phi = NULL_TREE;
@@ -8060,10 +8060,10 @@ vectorizable_live_operation (stmt_vec_info stmt_info,
          gimple *phi = gsi_stmt (gsi);
          if ((gimple_phi_arg_def (phi, 0) == lhs))
            {
-             remove_phi_node (&gsi, false);
              lhs_phi = gimple_phi_result (phi);
              gimple *copy = gimple_build_assign (lhs_phi, new_tree);
-             gsi_insert_after (&exit_gsi, copy, GSI_CONTINUE_LINKING);
+             gsi_insert_after (&exit_gsi, copy, GSI_NEW_STMT);
+             remove_phi_node (&gsi, false);
              break;
            }
        }

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

Kewen Lin <linkw at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hjl.tools at gmail dot com

--- Comment #5 from Kewen Lin <linkw at gcc dot gnu.org> ---
*** Bug 94449 has been marked as a duplicate of this bug. ***

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

--- Comment #6 from rguenther at suse dot de <rguenther at suse dot de> ---
On Thu, 2 Apr 2020, linkw at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443
> 
> --- Comment #4 from Kewen Lin <linkw at gcc dot gnu.org> ---
> This case has one conversion insn generated after bit_field_ref, the patch
> introduces one stupid mistake to use gsi_insert_before instead of
> gsi_insert_seq_before, it leads to miss the conversion insn.  The below patch
> makes it work. It also polishes copy related code a bit although not really
> necessary to make this case pass.
> 
> diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
> index c9b6534..4c2c9f7 100644
> --- a/gcc/tree-vect-loop.c
> +++ b/gcc/tree-vect-loop.c
> @@ -8050,7 +8050,7 @@ vectorizable_live_operation (stmt_vec_info stmt_info,
>    if (stmts)
>      {
>        gimple_stmt_iterator exit_gsi = gsi_after_labels (exit_bb);
> -      gsi_insert_before (&exit_gsi, stmts, GSI_CONTINUE_LINKING);
> +      gsi_insert_seq_before (&exit_gsi, stmts, GSI_SAME_STMT);
> 
>        /* Remove existing phi from lhs and create one copy from new_tree.  */
>        tree lhs_phi = NULL_TREE;
> @@ -8060,10 +8060,10 @@ vectorizable_live_operation (stmt_vec_info stmt_info,
>           gimple *phi = gsi_stmt (gsi);
>           if ((gimple_phi_arg_def (phi, 0) == lhs))
>             {
> -             remove_phi_node (&gsi, false);
>               lhs_phi = gimple_phi_result (phi);
>               gimple *copy = gimple_build_assign (lhs_phi, new_tree);
> -             gsi_insert_after (&exit_gsi, copy, GSI_CONTINUE_LINKING);
> +             gsi_insert_after (&exit_gsi, copy, GSI_NEW_STMT);

this should also use gsi_insert_before, otherwise if the first stmt
after labels has a use of lhs_phi then SSA will be corrupt.

> +             remove_phi_node (&gsi, false);

I prefer to have the PHI removed before you re-use its LHS.

OK with those changes.

>               break;
>             }
>         }
> 
>

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

--- Comment #7 from Kewen Lin <linkw at gcc dot gnu.org> ---
Yes, thanks Richi! I had the same update locally but didn't update here. The
latest whole patch is

diff --git a/gcc/testsuite/gcc.dg/vect/pr94443.c
b/gcc/testsuite/gcc.dg/vect/pr94443.c
new file mode 100644
index 0000000..f8cbaf1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr94443.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-march=znver2" { target { x86_64-*-* i?86-*-* } }
} */
+
+/* Check it to be compiled successfully without any ICE.  */
+
+int a;
+unsigned *b;
+
+void foo()
+{
+  for (unsigned i; i <= a; ++i, ++b)
+    ;
+}
diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index c9b6534..b621f89 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -8050,7 +8050,7 @@ vectorizable_live_operation (stmt_vec_info stmt_info,
   if (stmts)
     {
       gimple_stmt_iterator exit_gsi = gsi_after_labels (exit_bb);
-      gsi_insert_before (&exit_gsi, stmts, GSI_CONTINUE_LINKING);
+      gsi_insert_seq_before (&exit_gsi, stmts, GSI_SAME_STMT);

       /* Remove existing phi from lhs and create one copy from new_tree.  */
       tree lhs_phi = NULL_TREE;
@@ -8060,10 +8060,10 @@ vectorizable_live_operation (stmt_vec_info stmt_info,
          gimple *phi = gsi_stmt (gsi);
          if ((gimple_phi_arg_def (phi, 0) == lhs))
            {
-             remove_phi_node (&gsi, false);
              lhs_phi = gimple_phi_result (phi);
              gimple *copy = gimple_build_assign (lhs_phi, new_tree);
-             gsi_insert_after (&exit_gsi, copy, GSI_CONTINUE_LINKING);
+             gsi_insert_before (&exit_gsi, copy, GSI_SAME_STMT);
+             remove_phi_node (&gsi, false);
              break;
            }
        }

Still waiting for regression testing result.

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

--- Comment #8 from Kewen Lin <linkw at gcc dot gnu.org> ---
> 
> > +             remove_phi_node (&gsi, false);
> 
> I prefer to have the PHI removed before you re-use its LHS.
> 

Oops, missed this, will move it back when posting to email list.

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |meissner at gcc dot gnu.org

--- Comment #9 from Martin Liška <marxin at gcc dot gnu.org> ---
*** Bug 94451 has been marked as a duplicate of this bug. ***

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

Kewen Lin <linkw at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |clyon at gcc dot gnu.org

--- Comment #10 from Kewen Lin <linkw at gcc dot gnu.org> ---
*** Bug 94456 has been marked as a duplicate of this bug. ***

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[raj.khem at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

Khem Raj <raj.khem at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |raj.khem at gmail dot com

--- Comment #11 from Khem Raj <raj.khem at gmail dot com> ---
this patch seems to be causing gcc ICE on ARM when compiling lz4 sources in
kernel, lz4, vlc almost identical ICE is seen

attached is the test case please compile it with -O3

during GIMPLE pass: vect
lz4.c: In function 'LZ4_compress_fast_extState':
lz4.c:1180:5: internal compiler error: Segmentation fault
 1180 | int LZ4_compress_fast_extState(void* state, const char* source, char*
dest, int inputSize, int maxOutputSize, int acceleration)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~
Please submit a full bug report,

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[raj.khem at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

--- Comment #12 from Khem Raj <raj.khem at gmail dot com> ---
Created attachment 48170
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48170&action=edit
testcase

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

--- Comment #13 from Kewen Lin <linkw at gcc dot gnu.org> ---
(In reply to Khem Raj from comment #11)
> this patch seems to be causing gcc ICE on ARM when compiling lz4 sources in
> kernel, lz4, vlc almost identical ICE is seen
> 
> attached is the test case please compile it with -O3
> 
> during GIMPLE pass: vect
> lz4.c: In function 'LZ4_compress_fast_extState':
> lz4.c:1180:5: internal compiler error: Segmentation fault
>  1180 | int LZ4_compress_fast_extState(void* state, const char* source,
> char* dest, int inputSize, int maxOutputSize, int acceleration)
>       |     ^~~~~~~~~~~~~~~~~~~~~~~~~~
> Please submit a full bug report,

Same symptom:

for SSA_NAME: _1689 in statement:
op_1747 = _1689;
during GIMPLE pass: vect
lz4.c:1180:5: internal compiler error: verify_ssa failed
0x100d0ab verify_ssa(bool, bool)

Verified it can be fixed with posted patch in gcc-patch ML:
https://gcc.gnu.org/pipermail/gcc-patches/2020-April/543137.html

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

--- Comment #14 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Kewen Lin <linkw@gcc.gnu.org>:

https://gcc.gnu.org/g:4441ecedc3d74114683761901075085651928c52

commit r10-7531-g4441ecedc3d74114683761901075085651928c52
Author: Kewen Lin <linkw@linux.ibm.com>
Date:   Fri Apr 3 02:10:08 2020 -0500

    Fix PR94443 with gsi_insert_seq_before [PR94443]

    This patch is to fix the stupid mistake by using
    gsi_insert_seq_before instead of gsi_insert_before.

    BTW, the regression testing on one x86_64 machine from CFarm is
    unable to reveal it (I guess due to native arch sandybridge?), so I
    specified additional option -march=znver2 and verified the coverage.

    Bootstrapped/regtested on powerpc64le-linux-gnu (P9) and
    x86_64-pc-linux-gnu, also verified the fail cases in related PRs.

    2020-04-03  Kewen Lin  <linkw@gcc.gnu.org>

    gcc/
        PR tree-optimization/94443
        * tree-vect-loop.c (vectorizable_live_operation): Use
        gsi_insert_seq_before to replace gsi_insert_before.

    gcc/testsuite/
        PR tree-optimization/94443
        * gcc.dg/vect/pr94443.c: New test.

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

--- Comment #15 from Kewen Lin <linkw at gcc dot gnu.org> ---
*** Bug 94451 has been marked as a duplicate of this bug. ***

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

--- Comment #16 from Martin Liška <marxin at gcc dot gnu.org> ---
Can we close it as fixed?

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

Kewen Lin <linkw at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #17 from Kewen Lin <linkw at gcc dot gnu.org> ---
(In reply to Martin Liška from comment #16)
> Can we close it as fixed?

I guess so. Although this commit should be one part of backport for PR94393, I
guess I can only leave that bug open and close this one? Please feel free to
correct me.

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[florin.iucha at amd dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

Florin Iucha <florin.iucha at amd dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |florin.iucha at amd dot com

--- Comment #18 from Florin Iucha <florin.iucha at amd dot com> ---
*** Bug 94473 has been marked as a duplicate of this bug. ***

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[dpochepk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

Dmitrij Pochepko <dpochepk at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dpochepk at gmail dot com

--- Comment #19 from Dmitrij Pochepko <dpochepk at gmail dot com> ---
*** Bug 94532 has been marked as a duplicate of this bug. ***

[Bug tree-optimization/94443] [10 Regression] 510.parest_r and 526.blender_r ICE: verify_ssa failed since r10-7491-gbd0f22a8d5caea8905f38ff1fafce31c1b7d33ad

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94443

--- Comment #20 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Kewen Lin <linkw@gcc.gnu.org>:

https://gcc.gnu.org/g:7bce1c72444bb3c9636b492975a0494b376678cf

commit r9-8507-g7bce1c72444bb3c9636b492975a0494b376678cf
Author: Kewen Lin <linkw@linux.ibm.com>
Date:   Fri Apr 3 02:10:08 2020 -0500

    Fix PR94443 with gsi_insert_seq_before [PR94443]

    This patch is to fix the stupid mistake by using
    gsi_insert_seq_before instead of gsi_insert_before.

    BTW, the regression testing on one x86_64 machine from CFarm is
    unable to reveal it (I guess due to native arch sandybridge?), so I
    specified additional option -march=znver2 and verified the coverage.

    Bootstrapped/regtested on powerpc64le-linux-gnu (P9) and
    x86_64-pc-linux-gnu, also verified the fail cases in related PRs.

    Backport from mainline.

      2020-04-03  Kewen Lin  <linkw@gcc.gnu.org>

      gcc/
          PR tree-optimization/94443
          * tree-vect-loop.c (vectorizable_live_operation): Use
          gsi_insert_seq_before to replace gsi_insert_before.

      gcc/testsuite/
          PR tree-optimization/94443
          * gcc.dg/vect/pr94443.c: New test.